A Little Water

December 31, 2012 at 6:51 am (botany, ecology)
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by Carl Strang

For months now I have included a walk into the center of the stream corridor marsh at Mayslake Forest Preserve in my weekly rounds. When would water return? As I have documented this past year, the drought dried up the marsh, with the last surface water vanishing in mid-July.

The last puddle was here.

The last puddle was here.

The open mud quickly filled with a tall dense growth of an opportunistic plant, the river bulrush.

The bulrush transpired enough water that the marsh remained dry through the autumn.

The bulrush transpired enough water that the marsh remained dry through the autumn.

A recent all-day rain finally brought a little water into the marsh, as I discovered last week.

It is perhaps 3 inches maximum depth, and most has frozen.

It is perhaps 3 inches maximum depth, and most has frozen.

The area is at most 20-30 yards across.

The area is at most 20-30 yards across.

Not much yet, but it’s a start. I’m hoping to see the marsh full by spring, and will be interested in following its repopulation.

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Literature Review: Leaf Mine Diversity

December 28, 2012 at 6:59 am (ecology, insects (other), plant-eating insects)
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by Carl Strang

This week’s literature focus is on a paper that provided information suggesting why leaf miners produce such diverse mine structures.

Leaf miners are larval insects so tiny that they fit between the upper and lower leaf surfaces, feeding on the tissues in between. This example is a twisting linear mine on Heracleum.

Leaf miners are larval insects so tiny that they fit between the upper and lower leaf surfaces, feeding on the tissues in between. This example is a twisting linear mine on Heracleum.

Ayabe Y, Ueno T (2012) Complex Feeding Tracks of the Sessile Herbivorous Insect Ophiomyia maura as a Function of the Defense against Insect Parasitoids. PLoS ONE 7(2): e32594. doi:10.1371/journal.pone.0032594

They looked at linear mines in a fly that develops in a French aster. In their review they mention research that has been done on various mine forms and how they may deter parasitoids. Parasitoids focus mainly on the upper leaf surface, so lower surface mines (including tentiform mines of Phyllonorycter moth caterpillars in some of our local plants) provide some protection, and upper surface miners sometimes shift to the lower surface to pupate. Blotch mines provide more escape space for their occupants. In this study they found that complex linear mines, especially ones that have branches and crossing tunnels, reduce parasitoid effectiveness.

We can see a wide range of leaf mine types on our local plants.

Expanded blotch-type mine on poison ivy (the leaves aren’t always 3 leafleted!).

Expanded blotch-type mines on poison ivy (the leaves aren’t always 3 leafleted!).

The outline of a tentiform mine shows on this maple leaf. The mine is on the underside of the leaf, not readily reached from above.

The outline of a tentiform mine shows on this maple leaf. The mine is on the underside of the leaf, not readily reached from above.

According to this research, it boils down to a game of hide-and-seek. If a leaf miner can make its mine complex enough, or in a place where it is difficult to reach, or expand the mine to the point where finding the miner is somewhat needle-in-haystackish, it gains an advantage over the insects that would parasitize and kill it. Furthermore, the diversity of mine types provides a more complex evolutionary puzzle for the parasites as a whole to solve.

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Lessons from Travels: Turtle Range Gap

December 27, 2012 at 7:02 am (ecology, reptiles and amphibians)
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by Carl Strang

There are many sorts of comparisons that can be made between our region at the southern end of Lake Michigan and other parts of the world. Today’s focus is on a puzzling absence. I loved turtles as a child, and enjoyed encountering eastern box turtles and ornate box turtles in the woodlands of north central Indiana where I grew up.

The eastern box turtle (shown) is a forest dweller. The ornate box turtle is a prairie species that has become rare in Indiana.

The eastern box turtle (shown) is a forest dweller. The ornate box turtle is a prairie species that has become rare in Indiana.

When I lived in south central Pennsylvania I got the opportunity to conduct an ecological study of eastern box turtles and wood turtles, whose ecological differences I summarized in an earlier post.

The wood turtle, like the eastern box turtle, lives in forests.

The wood turtle, like the eastern box turtle, lives in forests.

When I moved to northeast Illinois, I was disappointed and somewhat puzzled to learn that none of these three semi-terrestrial species lives here. After pondering this absence off and on for some years, I feel ready to pose a hypothesis. In the case of the box turtles, I think it has to do with our soil. Box turtles bury themselves in upland places to hibernate for the winter.

A box turtle emerges from its sandy-soil hibernaculum in spring.

A box turtle emerges from its sandy-soil hibernaculum in spring.

Our northeast Illinois soil is derived from a clay parent material, ground up New Albany shale which the Lake Michigan lobe of the last continental glacier left behind as part of its legacy. Bricks are made of clay. It’s a difficult material to dig in, whether for gardening or for hibernating, and I suspect this is what is blockading the eastern box turtles, which live east and south of us, and the ornate box turtles, which live west and south of us.

As for the lack of wood turtles, that is perhaps a simpler puzzle to solve. Wood turtles live in forests, and our region historically was prairie punctuated by more open, drier woodlands. Here the wood turtles appear to be replaced by Blanding’s turtles, which live in prairies and their adjacent wetlands in much the same way that wood turtles made their living in the lowland eastern forests, spending some of their time (and hibernating) in the marshes, ponds and streams, but emerging frequently to forage on drier prairie land. Perhaps I am influenced by my childhood experience here as well. Most of our local landscape in Indiana historically was a mix of prairie and dry to mesic woodlands on sandy soil. We had eastern box turtles, ornate box turtles, and Blanding’s turtles, but no wood turtles.

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Flame-shouldered Dart

December 26, 2012 at 7:24 am (ecology, plant-eating insects)
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by Carl Strang

Old notes, photos and memories are worth recording and keeping, as they can produce results as new information becomes available to illuminate them. Back in the 1980’s as I surveyed plant-eating insects in Maple Grove and Meacham Grove Forest Preserves, I was able to identify most of the species I encountered, but I tried to get photos of all, and kept notes and records. That research introduced me to the important component community concept. This is the idea that each kind of plant (or each group of plants that use similar chemical defenses) is consumed by a particular suite of insects and other herbivores adapted to defeating those defenses, and this is a helpful way to organize many of the species in a forest or other community. One of the component communities in the study forests was based on Smilacina racemosa, the feathery Solomon’s plume or false Solomon’s seal.

Feathery Solomon’s plume

Feathery Solomon’s plume

In one of the first posts in this blog I described that component community, and mentioned that I was unable to identify two of its members. Later I found a resource that allowed me to narrow down one of the mystery insects, a sawfly, to genus Phymatocera, either P. offensa or P. similata.

One of the Phymatocera sawflies consuming Smilacina flowers

One of the Phymatocera sawflies consuming Smilacina flowers

Recently I ran across a photo in the excellent Wagner guide to caterpillars that allowed me to identify the other unknown. It proves to be the flame-shouldered dart (Ochropleura implecta), a moth in the owlet moth family Noctuidae.

Flame-shouldered dart caterpillar on Smilacina

Flame-shouldered dart caterpillar on Smilacina

As is the case with many noctuids, however, this one has a fairly broad diet across its range, so its presence on this particular plant provides only a little information. Nevertheless, it’s always nice to solve an old mystery.

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Northern Shoveler Species Dossier

December 21, 2012 at 7:18 am (birds, species dossiers)
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by Carl Strang

In honor of the shovelers we saw during our Christmas Bird Count on Saturday, here is my somewhat paltry dossier of observations on this duck, which is strictly a migrant in our area. According to researchers their main direction of travel through northern Illinois is unusual: east-west, between the Atlantic coast and prairie breeding grounds.

Shoveler, Northern

Pair of northern shovelers, western Alaska

Pair of northern shovelers, western Alaska

I have seen these ducks regularly on Lake Maxinkuckee and Hawk Lake in Indiana during migration. Usually they travel as singles, pairs or in small groups. Males have a peculiar zipping call, noted in western Alaska, where occasionally I saw widely scattered individuals and pairs. There also was a call reminiscent of a flipped strip of metal. Usually they feed by sifting the surface of the water with sideways movements of their extraordinarily large bills.

15MR87. Shovelers were in a temporary pond along Geneva Road east of West Chicago.

20MR99. First shoveler of the year, IL.

26MR00. I observed 5 males and 1 female shoveler at McKee Marsh, 20 yards offshore, sticking their beak and sometimes their heads fully in the water and swinging them back and forth, but not tipping up.

24SE00. Several shovelers in small groups feeding at McKee Marsh, skimming the surface of the water.

Shovelers on May’s Lake

Shovelers on May’s Lake

14OC00. About 20 shovelers at McKee Marsh, all feeding by tipping up in contrast to their usual feeding style. No floating algae, and the water area still is large, though the entire corridor to the outlet is dry. Mainly they are in the center of the pool, though a few near the edge also are tipping up.

15DE12. A number of late-migrant shovelers were tipping up in the large pond in Timber Ridge Forest Preserve on the north side of Geneva Road.

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Literature Review: Biodiversity, Evolution and Time

December 20, 2012 at 7:03 am (ecology, restoration)
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by Carl Strang

Today I hope to illustrate how different studies can be made to illuminate one another. The starting point is a paper that I think has the potential to be profoundly influential in the field of community ecology.

Lowland tropical forests are renowned for their high biodiversity. They also are old.

Lowland tropical forests are renowned for their high biodiversity. They also are old.

Reich, Peter B. 2012. Impacts of biodiversity loss escalate through time as redundancy fades. Science 336:589-592.

Studies of biodiversity in plant communities have suggested that the number of species climbs to a saturation point, after which additional species do not add more biomass productivity and apparently could be removed without affecting ecosystem function. In contrast, this long-term study shows that the added species refine their niches over time, and by sorting out and separating niches they eventually produce a unique portion of niche space for every species.

This result reminds us that our focus on the day-to-day or year-to-year dynamics of ecosystems needs to be tempered by the fact that ecological roles are flexible in evolutionary time. Species that begin as competitors, but which persist together, can subdivide whatever resources are the basis for their competition, as selective pressures nudge them apart. This process provides a mechanism which in part explains the results of the next featured study.

Jetz W, Fine PVA (2012) Global Gradients in Vertebrate Diversity Predicted by Historical Area-Productivity Dynamics and Contemporary Environment. PLoS Biol 10(3): e1001292. doi:10.1371/journal.pbio.1001292

(Also interpreted in an accompanying commentary by another author). They found that 80% of the variation in vertebrate species diversity between different terrestrial biomes is accounted for by a combination of ecosystem area, age, productivity and temperature, with the highest diversity in warm tropical forests. Thus evolutionary as well as ecological factors are important. Area alone provided a poor fit. Age was considered up to 55 million years, and age combined with area improved the fit greatly (for instance, grassland ecosystems are extensive but relatively young at 8 million years). Productivity and temperature separated deserts from tropical forests, for example, and further improved the model. Productive areas have more individuals, and thus greater potential for evolutionary diversification, and also have greater ecological space for niche diversification. Finally, they looked at ecological influences by dividing biomes into finer-grained divisions (down to a 110 km grid), and found that this further refined the results, again by variation in productivity of the smaller areas. This points to ecological interactions having an influence on local biodiversity.

The connection to the ideas in the first paper should be clear. The connection to the next one is less obvious.

Franzén M, Schweiger O, Betzholtz P-E (2012) Species-Area Relationships Are Controlled by Species Traits. PLoS ONE 7(5): e37359. doi:10.1371/journal.pone.0037359

They studied Lepidoptera on islands off the coast of Sweden to consider species richness-island area relationships and the niche and other ecological or physiological traits that may contribute to the overall pattern. They found a number of traits that had an impact on species-area relationships, and in general these made ecological sense. Examples of traits which were particularly sensitive to island area were low reproductive potential, small range size, narrow diet breadth, and low abundance. Thus classical island biogeography, which simply measures species area relationships and considers gross immigration and extinction rates, is improved in its explanatory power by consideration of traits that contribute to ease of immigration and resistance to extinction.

Here the communities under consideration are on islands, and once immigration has occurred the stage is set for the kinds of ecological-evolutionary processes outlined in the first paper above. This produces phenomena like the famous Darwin finches of the Galapagos, and innumerable other examples.

Moreno-Mateos D, Power ME, Comín FA, Yockteng R (2012) Structural and Functional Loss in Restored Wetland Ecosystems. PLoS Biol 10(1): e1001247. doi:10.1371/journal.pbio.1001247

Schmitz OJ (2012) Restoration of Ailing Wetlands. PLoS Biol 10(1): e1001248. doi:10.1371/journal.pbio.1001248

These two papers provide an interesting contrast in interpretations. The first is a review of studies in which wetland restorations were compared to undisturbed baselines. The authors concluded that restoration has some success but falls significantly short of the return to ecosystem structure and function that is the goal of restoration. Thus they caution that wetland destruction should not be regarded as something that can be mitigated by restoration. Schmitz looks at their results and comes to the opposite conclusion, suggesting that wetland restoration is a thoroughly successful process, but makes no attempt to reconcile his conclusion with theirs.

Here the value of the first paper at the top of this post is to remind us that there is a pitfall in thinking about results over too narrow a time frame. Restoration is valuable and good, but in the short term it cannot be thought of as completely replacing the original. There is no way to re-create all the intricacies of the co-evolved relationships Reich wrote about. It’s much better to preserve the original. Nevertheless, restoration is worth doing, and given enough time there is hope that something as good as the original will evolve. If we can at least preserve as many species as possible, that will minimize the time needed for such a dynamic endpoint to be reached.

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Lessons from Travels: Desert Plants

December 19, 2012 at 7:15 am (birds, botany, ecology, Lessons from Travels)
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by Carl Strang

Last week’s focus was on some commonalities between plants of the Alaskan tundra and those of Illinois. Today it’s about contrast. There is not much that seems familiar in the dominant plants of the continent’s southwestern deserts. It’s worth the trip just to see some of the iconic species:

Joshua trees. Note the cumulus cloud that has formed above the mountain, where convection is carrying the paltry bit of humidity up to where it meets air cool enough for condensation.

Joshua trees. Note the cumulus cloud that has formed above the mountain, where convection is carrying the paltry bit of humidity up to where it meets air cool enough for condensation.

Saguaro, hundreds of years old.

Saguaro, hundreds of years old.

And my favorite, the ocotillo.

And my favorite, the ocotillo.

Here’s a closer look at ocotillo in leaf:

During the relatively brief time when the ocotillo is not just bare branches, its stems become covered with tiny leaves.

During the relatively brief time when the ocotillo is not just bare branches, its stems become covered with tiny leaves.

These little leaves photosynthesize like mad in the desert sun, taking advantage of a brief period when there’s enough soil moisture to support them. Surviving on low rainfall is the theme in desert plant ecology, and various plants accomplish this in different ways. Cacti photosynthesize in thick, wax coated stems rather than moisture-draining leaves.

Cactus in bloom, a Mammillaria, I think. The leaves are in the form of protective needles.

Cactus in bloom, a Mammillaria, I think. The leaves are in the form of protective needles.

Animals can take advantage of those needles’ protection.

Cactus wren nest in a walking stick cholla cactus.

Cactus wren nest in a walking stick cholla cactus.

Another dramatic sign of moisture limitation is the plants’ spacing.

Note the bare soil areas between these evenly spaced plants.

Note the bare soil areas between these evenly spaced plants.

Their roots have staked out territories as surely as a great horned owl’s hooting. This moisture’s mine!

Photos can only partly convey the beauty of these places, and the value of their quiet. Photos cannot begin to express the sensations of heat, of sun, of the dry air. Also there’s some history missing. Many of these desert places were grasslands, the grasses growing when they got moisture, then allowing their tops to senesce in dry times like the ocotillo. Cattle grazing converted many desert grasslands to desert shrublands, as Aldo Leopold and other early ecologists pointed out (I believe this is true in particular of the last photo above, dominated by creosote bush, which not only has small waxy leaves but is distasteful to cattle).

The deserts are worth exploring and experiencing, if only to help us understand our own home landscape better.

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Where are the Galls?

December 18, 2012 at 7:02 am (botany, ecology, plant-eating insects)
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by Carl Strang

In site monitoring we are recording the ongoing story of a place, and change is the currency in which we trade. Some changes are easier to notice than others. When something newly appears on the scene, there is a good chance we will pick it out. A tree is down that was standing the previous day. A bird new to the site starts singing. The mother raccoon’s tracks now are accompanied by her babies’.

Less easy to notice are absences, things that have failed to appear as usual, especially if they are small. Such was the case for me this year at Mayslake Forest Preserve with respect to the goldenrod galls. Last week as I made my way through the prairies and meadows, I realized that there were very few galls, and I started to pay attention. I saw no spindle galls of the moth caterpillar (Gnorimoschema gallaesolidaginis), but usually there are few of those anyway. In the three previous winters there were dozens to hundreds of bunch galls (produced by the midge Rhopalomyia solidaginis ) and especially of ball galls (stimulated by the gall fly Eurosta solidaginis) along the route I was taking.

A goldenrod bunch gall

A goldenrod bunch gall

This year I counted 2 bunch galls and no more than 15 ball galls. If only one species were involved, I would suspect that a specialized disease or parasitoid had caught up with them and caused a population collapse. There were two, however, and furthermore they belong to different families of insects.

A goldenrod ball gall

A goldenrod ball gall

The ball galls mostly were in little bunches, suggesting that each group was the product of a single female. The places they were clustered seemed unremarkable, though possibly the plants were larger in those spots (smaller and thinner in most places). It seems unlikely that parasites of both species would have knocked them down in the same year. It’s tempting to blame the drought for all of this, as it was the oddest aspect of this past year, but it’s also true that the winter was relatively mild, and other factors I haven’t perceived may have come into play. For now this must remain an open question.

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Editorial: On Guns

December 17, 2012 at 7:33 am (Uncategorized)
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by Carl Strang

The horror of the tragedy last week in New England raises again the debate in America regarding guns. Today I am taking a step away from the usual content of this blog to register my current thoughts on this issue. My roots are in rural Indiana, and I come from a family in which hunting and fishing are important traditions. We were taught by my Dad to regard guns as tools for obtaining food. There was a recreation component to hunting: that enjoyment of an outdoor activity, that relationship to wildlife, contributed to my development as a scientist and natural historian (such is the admittedly tenuous connection to this blog).

Goldeneye ducks prior to preparation for the table, harvest of a day’s hunt in my teenage years.

Goldeneye ducks prior to preparation for the table, harvest of a day’s hunt in my teenage years.

The most important lesson from hunting, in my view, is the direct experience of the fact that our lives depend upon the death of others. I felt the visceral, poignant sense of loss of life when I considered that my decision to shoot ended the life of a free wild animal. At the same time there was something honest about it. I took that life myself, rather than indirectly through a butcher or grain harvester (as a budding biologist I had the wisdom to realize that a plant’s life is no less valuable than an animal’s; also, this is why I minimize the collecting of insects in my research).

As I said, we regarded guns as tools. Dad’s approach to guns was no different than his approach to the band saw. We were to stay away from that power saw, and from guns, until he decided we were old enough. There was instruction on safety, and respect for the danger potential in the misuse of those tools. The idea of ending a human life with our shotgun or rifle was as abhorrent and insane as would be the ending of a human life with the saw.

My central point is that if we as a society were to regard guns as tools, we would take a step forward in resolving the gun issue. We are at a point now where people on both sides of this debate are thinking of guns too abstractly and too monolithically, either with phobic hysteria or as objects of worship. In fact there are different categories of guns as tools. There are guns specialized for hunting, guns specialized for target shooting, and guns specialized for killing people.

A categorization of guns as tools would, I hope, forward the debate and defuse some of the fear and hysteria on both sides. An acknowledgement of the legitimacy of guns for hunting and for target shooting might convert mindless generic fear to conditional acceptance on the anti-gun side, potentially removing some fear of the unknown there. Acknowledgement that some guns are in fact designed to kill people might ultimately prove to the pro-gun side that guns don’t have to be regarded monolithically. I have seen pro-gun arguments that the way to avoid school gun tragedies is to convert all teachers to gun-packin’ buckaroos. I won’t honor such idiocy with further consideration.

There is no need for civilians to own assault weapons, automatic rifles or other guns designed to kill people. The pro-monolithic-gun side is fond of raising the slippery slope argument, an argument based on fear, and one I don’t buy. The “civilians” qualifier is significant. I have no quarrel with the military. I don’t pretend to be a constitutional scholar, but the point about guns in the Constitution is based on a reference to a militia. To my thinking, that means that someone needs to be a certified member of a society-sanctioned military group to be a legal owner of a specialized human-killing weapon. The ready sale and supply faucet for the things needs to be closed.

I also don’t buy the implied argument that one can defend oneself from a gun only with a gun. Popular culture has filled people’s heads with fantasies.

We need to move away from placing guns in a special category. We need to think of them as tools. Were we to get to that point, the use of a gun to kill a person might again be regarded with the same sense of inappropriateness that we now regard the use of a hammer, pillow or other mundane object in ending someone’s life.

I realize that few, perhaps none, of the readers of this blog will agree with every point I have made. I hope only to nudge the debate away from the abstract and toward the concrete, from abstract absolutist thinking to a more concrete and pragmatic approach.

Footnote: A point that needs to be considered in this debate, and which I saw no place to insert in the above argument, is the impersonal nature of a gun killing. Ending a person’s life with one’s bare hands or even a knife requires an intimacy and closeness that necessitates a certain craziness. A gun kills at a distance. One can kill, turn one’s back and walk away without having touched the victim. When we killed a duck or squirrel, we then took it and processed it for the table, so in the hunting context the intimacy was retained.

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Olive-sided Flycatcher Species Dossier

December 13, 2012 at 7:12 am (birds, species dossiers)
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by Carl Strang

This week’s species dossier is for contrast. Though I have seen olive-sided flycatchers in several spring migration seasons in recent years, I have not been able to add anything significant to the first account I made in 2000. Prior to then, I had heard one calling its “quick three beers!” at Maple Grove Forest Preserve one spring in the mid-1980’s. I have never observed them in their North Woods breeding grounds, and I have not observed them during the fall migration.

Olive-sided flycatcher

Olive-sided flycatcher

Flycatcher, Olive-sided

25MY00. Willowbrook. Olive-sided flycatcher foraging from branches high in dead trees. Its bill is enormous, and its head large, giving it a distinctive look. This one was yellow in vent area. It was distinguished by the lack of an eye-ring and wing bars, along with the narrow light-colored channel between the dark sides of its breast. It never vocalized.

And that’s it. I have seen the species again at Willowbrook, at Fullersburg, and at Mayslake, but the story always has been the same. I limit the dossier to observations I have made myself. Of course, those observations are informed by what others have discovered, in this case that the large muscular head is an adaptation for crushing the hard exoskeletons of bees, wasps and other armored insects upon which this flycatcher feeds. Such prey become more active and abundant later in the season, so this species is one of the later migrants. I have never heard one call other than that one time in the 1980’s.

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